Apparatus for drying webs of paper or the like



OC- 2 1962 E. A. 'rxMsQN 3,056,593

APPARATUS FOR DRYING WEBS 0F' PAPER OR THE LIKE Filed Feb. 16, 1959 2Sheets-Sheet 1 Inventor @Qua-197- maf? 779450@ Oct. 2, 1962 E. A. TIMSON3,056,593

APPARATUS FOR DRYING WEBS OF PAPER OR THE LIKE Filed Feb. 16, 1959 2Sheets-Sheet 2 A ltorneys United States Patent iifice 3,056,593APPARATUS FOR DRYING WEBS F PAPER 0R THE LIKE Ernest A. Timson, 75Northampton Road, Kettering, England Filed Feb. 16, 1959, Ser. No.793,591 Claims priority, application Great Britain Feb. 19, 1958 2claims. (ci. 26S- 3) This invention appertains to apparatus for dryingtravelling webs of relatively thin and tiexible material such as paper,cloth, lm, foil or the like after such webs have been operated upon by,or treated in, a process involving the deposition of moisture or certainmaterials upon, or the application of inks, stains, dyes or otherliquids to, surfaces of the webs.

For convenience in the following further description 'and in theappended claims, the single term paper will be used in a generic senseto include relatively thin and llexible webs of any appropriate materialanalogous to paper.

Thus, for instance, a continuously travelling web of paper operated uponor treated as aforesaid may require to be dried prior either tore-reeling or spooling or to division into separate sheets or pieces.

Although there is no limitation in this respect, it is primarily theintention to embody the invention in an apparatus of the class suitablefor drying travelling webs of paper after they have passed through aprinting machine and been printed upon with a volatile ink or likemedium, the purpose of the drying process in this instance being toexpedite evaporation of the solvent in the medium, Such an apparatus isalso suitable for the drying of lms by, for instance, penetration,polymerization, oxidation and other drying processes all of which areaccelerated by heat. The fusion of powders distributed on webs, as inelectronographic methods of printing, is another process capable ofbeing carried out by an apparatus of the class concerned.

The primary object of the present invention is to provide, in aweb-drying apparatus, an improved relative arrangement of web guidingmeans and web heating means so designed as to dry travelling webs ofpaper more expeditiously, and hence economically, and also moreeiciently, than heretofore.

The apparatus constituting this invention includes, in combination,means adapted so to guide two travelling webs of paper through a dryingzone that the webs have runs with a space between them, and meansarranged to supply between the said spaced runs heat which plays on theopposed surfaces of, and is trapped between, the webs.

Conveniently, the said web guiding means may be so disposed as to beadapted to guide through the drying zone two kwebs having straight runswhich extend a short distance only apart with a clear space betweenthem.

`Although the means for supplying heat between the webs may be of any`suitable character and even comprise, for instance, electric heaters,it is primarily the intention to provide, within or adjacent to thedrying zone, burner means communicating with a supply of combustiblefuel and so formed and disposed as to be adapted, when lighted, todirect a jet or jets of naked ilame into the space between the two webs.

Thus, the idea is that the heat, e.g. naked ame, shall play between theopposed surfaces of the spaced straight runs of the travelling webs, theheat or flame being thereby enclosed and trapped by the paper. In thisway greater eiciency in drying is achieved by virtue of the fact thatthe heat or flame is contained by the webs of paper and prevented frombeing diverted from its most effective position by stray draughts ofair. An additional 3,956,593 Patented Oct. 2, 1962 and importantadvantage of the improved arrangement is, of course, that two webs aresimultaneously dried, thereby expediting the drying process.

The burners, when provided, may each be of a form designed to produce,by admixture therein of combustible fluid fuel, e.g. coal gas, with airat atmospheric pressure, an only moderately hot, in contradistinction toa high temperature, ilame which issues lazily from the burner suchwiseas to be carried along, and to ilow together, with the travellingmaterial to be dried. The form of each of the burners may additionallybe such as to produce a llame of known fan shape akin to that of a batswing, i.e. a laterally spread, flat ame which is very wide in relationto its thickness.

The adoption of the present invention is manifestly advantageous inconnection with certain printing machines wherein it is customary to runon adjacent courses two webs both of which need drying. In other casesthe same web `needs drying twice. This latter necessity arises when oneside of the web has to be printed upon and dried before the other. Suchcommonly occurs on web fed letterpress rotary perfecting presses.Accordingly, the eX- pression two travelling webs used herein isintended to include not only two entirely separate webs, but also twospaced runs, travelling on adjacent courses, of the same web.

In order that the invention may be more clearly understood and readilycarried into practical effect, a specic arrangement of the improvedweb-drying apparatus will now be described with reference to theaccompanying purely diagrammatic drawings, wherein:

FIGURE l is a diagrammatic longitudinal sectional view of the apparatusshowing gas burner ames directed into the space between two travellingwebs of paper,

FIGURE 2 is a plan view of the same, but with the drying chamberremoved, and portions of the upper web torn away to disclose moreclearly the gas burners and the form of the flames issuing from thenozzles of the latter, and

FIGURES 3 and 4 are side and front views respectively of one of the gasburners employed.

Referring to FIGURES l and 2 it will be seen that the improvedweb-drying apparatus comprises a horizontally disposed box-like dryingchamber 1 the interior of which constitutes a drying zone. The entranceinto one end of this chamber is in the form of a rectangular apertureindicated at 2. Similarly, the exit from the opposite end of the saidchamber is in the form of a further rectangular aperture 3. Adjacent tothe entrance aperture 2-on the outside of the relevant end of thechamber 1-is a pair of web guiding rollers 4 and 5. These rollers aredisposed one above the other with a space between them, and they may berelatively adjustable heightwise to Vary the depth of the said space. Inthis regard, for example, the spindles 4a and 5a of the rollers may, asshown in FIGURE l, be mounted in arms 6 which are adjustable in or onthe framework of the apparatus (not shown). One web W of paper travelsbeneath the upper entrance roller 4 and longitudinally right through thechamber 1, whilst a second web W travels over the lower entrance roller5 and similarly through the chamber, the two webs passing through theexit aperture 3 and respectively beneath and over a pair of superimposedexit rollers 7 and 8. Associated with the rollers 7 and S are furtherrollers 9 and 19 for the guidance of the two webs. The distance apart ofthe two webs W and W at the exit aperture 3 may, if desired, also bevaried by adjustment of the rollers 7 and 8. In any event, the pairs ofguide rollers 4 and 5 and 7 and 8 are so disposed as to guide throughthe drying chamber 1 two straight runs of the webs W and W which extenda comparatively 3,056,593 s Y r short distance only apart with a clearspace S between them.

These runs may either extend parallel or substantially so to one anotheror they may, as shown in FIGURE l, converge for a purpose presently tobe described herein. That is to say, in the example illustrated, thewebs W and W are made to run closer together towards their exit from thedrying chamber 1.

Where the webs are printed upon with ink, the rollers 7, 8, 9 and 10 maybe water-cooled rollers the function of which is to cool down the websand the printing on them to below the sticky temperature of the driedink which, even when dry, is often thermoplastic. Also the paper tendsto suffer if it is kept at, say, 300 C. for a longer time than it takesfor it to travel through the chamber 1.

In the illustrated example, there is provided, immediately in advance ofthe pair of entrance rollers 4 and 5, a transversely extending fluidfuel pipe or manifold 11 which extends at right angles to thelongitudinal edges of the travelling webs of paper. The pipe or manifold11 is connected to a supply of any suitable combustibie fluid fuel, e.g.coal gas, the flow of which through the said pipe or manifold mayadvantageously be controled by adjustment of a valve provided at 12 (seeFIGURE 2). The pipe or manifold 11 may advantageously be furnished withtwo or more suitably spaced burners such as 13 each in the form of ahollow jet having in its outer, mainly closed end a comparatively smalloutlet aperture communicating with a comparatively wide recess which hasan inwardly, e.g. concave, bottom designed to achieve diusion of thecombustible fluid issuing through the said aperture and at the same timeproducing a wide thin ame of fan or bats wing shape acquiring thesufficiency of air for complete combustion by free turbulence. Suchwide, thin flames are depicted at F in FIGURE 2, and since the hollowburner jets extending from the common pipe or manifold 11 extendactually between the entrance rollers 4 and 5, then these flames aredirected into the space S between the webs W and W which space isaccordingly lled with flame.

Although it is primarily the intention to supply burners of the formjust described with coal or Town gas, there is no limitation in thisrespect since manifestly the burners could be supplied with any suitablefuel gas, such as methane or butane, or ywith liquid fuel such as oil orparaffin vapour, the fluid fuel being mixed with air at atmosphericpressure when necessary. But, especially when coal or Town gas is to beused, it is advantageous to employ aerated burners of the particularkind known as Hypact burners developed by the Research Laboratory of theGas, Light and Coke Company in the United Kingdom. Such a hollowcylindrical burner indicated at 13 in FIGURES 3 and 4, is in the natureof an enlarged industrial jet fabricated throughout in metal and adaptedto be connected on to the end or branch of a gas pipe. In the outersurface 13a of the comparatively thick mainly closed end 13b of theHypact burner is milled a diametral concave recess 14. In the bottom ofthis recess, centrally between its ends, is a small rectangular outletaperture 15 communicating with the hollow interior 16 of the cylindricalburner 13, this aperture 15 being produced by forming in the innersurface 13e of the aforementioned mainly closed end a diametral channelextending at right angles to the milled concave recess 14 (see FIGURE4). By virtue of the formation described a marked degree of aeration isobtained by turbulence.

Each of the burners 13 is accordingly of such a form as to be adapted toproduce by admixture therein of combustible uid fuel with air atatmospheric pressure, an only moderately hot, in contradistinction to ahigh temperature, llame which issues lazily from the burner suchwise asto be carried along, and to How together and in contact, with thetravelling material to be dried.

By an only moderately hot flame vis meant one of the average order offrom 900 to 1400 C., depending on the zone considered, incontradistinction to an intensely hot flame of anything up to 2,200 C.In this regard it has to be borne in mind that a lazy flame compriseszones of various temperatures.

The longitudinal flow of the flames F usually in the direction ofmovement of, and hence in company with, the travelling webs iscomparatively sluggish since there is no forced draught and blast of airthrough the burners directing the flames straight at the material. Inother words, the flames issuing from the burners spread longitudinallyas well as transversely with respect to the path of travel of the spacedwebs. The travelling webs are accordingly contacted by gentle flameswhich have a comparatively large area in contact with the webs.

Moreover, these flames, being effective over comparatively large areasof the travelling webs and notwithstanding the fact that `thetemperature of the flames is only moderate, is adequate to dry, say, inkprinted on paper and avoid the necessity to concentrate-repeatedly asnecessary-a substantially more intense heat upon much smaller areas ofthe material. As a consequence, any tendency to alter the physicalproperties `and dimensions of the paper during drying is minimised.

Large volume, low temperature flames, i.e. lazy or slack ames areadvantageous for the purpose in view since they are of considerablepersistence. Now such flames, when formed below a travelling web ofpaper freshly printed on both sides, may efficiently transfer the heatso that the whole web is uniformly warmed to a temperature of 300 C. orover in times that are available for webs travelling at speeds up to andin excess of 1000 ft. per minute. This temperature is that at which thespecial inks used for this drying process will dry in the times allowedbut at which, in this time, the paper does not suffer. It has been foundthat the use of bats wing burners results in a whole length of paper webin a drying chamber carrying flame below it for a distance of 4 to 7ft., is effectively dried. It will be appreciated that a persistent lazyame pressing against a web has exceptionally good opportunities ofdelivering a large proportion of its heat to the paper since it soondisplaces the dead air film invariably carried along by such a web, andby virtue of the comparatively low relative velocity between the flameand the web the ame can make continuous intimate contact with theunderside of the web as long as any flame persists. This arrangementresults in the use of less gas for a given amount of drying, thanprevious known methods in a convenient short length of web run. Thus,with these facts in mind, it will be readily appreciated that lazy orslack flames issuing from burners such as 13 can, for the sake ofefliciency, be directed into the space S between the two webs W and W'with every hope of successfully dispensing with the necessity for anyflames below the lower web W', providing care is taken to ensure thatthe said space is entirely filled with ames. Any departure from thiscondition results in poorer heating of the lower web W', and it isgenerally necessary, of course, that both webs should be heatedsubstantially the same amount.

In most cases it is possible to arrange Hypact or equivalent gas burnersbetween two spaced webs at the beginning of their travel, as illustratedin the drawings, but in those cases where the webs require to be closertogether (because only a small flame is required which would not ll awider space of `suficient depth to accommodate the burners withoutcontact) the burners may be mounted in advance and clear fof theadjustable guide rollers 4 and 5 around which the webs run beforetravelling on their spaced courses through the drying chamber 1. A flatlazy flame `or flames in this case is or are directed at the entranceinto the space S between the webs and is or are drawn in between thewebs to fili the space between them.

It may be mentioned here that the guide rollers 7 and 8 and 9 and 10need not necessarily be water cooled because they are, in fact, cooledby the continuous feed of cold paper over them through which paper theflame heat has no time to penetrate.

Because each lazy flame is consumed during its travel along with andbetween the Webs it will diminish in volume as it travels and the websare therefore preferably made to converge as previously mentioned hereinso that the space between them is for at least the major portion of itslongitudinal dimension completely filled with flame, while such amepersists at all. In FIGURE 2, the transverse chain line 17 indicates thelength of the flames F, this length being variable, within limits, byappropriate control of the fuel ilow through the burners 13.

`Obviously the spent products of combustion from the now dead flame orflames will issue from the gap between the exit rollers 7 and 8, andprovision for exhaust has to be made to take these products away toatmosphere; also the similar products which escape laterally frombetween the webs W and W travelling through the drying chamber 1 have,of course, to be exhausted.

One great advantage of two web apparatus is that the Webs can travel atany inclination without altering the eiciency.

The lazy dames produced by the burners 13 are substantiallynon-luminous, or weakly luminous, so as just to avoid the deposition ofcarbon upon the opposed surfaces of the two webs being dried. The factthat each of the llames F is of a fan shape akin to that of a bats wingreduces to a `minimum the number of burners required adequately to coverthe full width of the webs.

It may in appropriate cases be advisable to provide above the upper webW a row of small burners to burn olf the volatile products given olffrom drying ink. In FIGURE 1, a pipe or manifold common to such a seriesof burners is indicated diagrammatically at 18.

The burners may, if desired, be movable from an operative position inwhich the or each jet of naked flame is freely directed into the spacebetween the straight runs of the travelling web to an inoperativeposition in which the flame is directed safely away from both webs, the`arrangement being designed to avoid damage to the webs in the event oftheir travel being interrupted.

The speed of the travelling webs is, of course, related to the intensityof the jet or jets of dame issuing from the burners.

Means may, if desired, also be provided for reducing, i.e. turning down,the flame jet or jets simultaneously with movement of the burners intotheir inoperative positions. Conversely, such means would be reverselyoper- 6 able to turn tup the arne jet or jets each time the nozzle meanswere restored to their normal operative position.

It is preferred that both webs travel in the same direction-away fromthe burners. The web -run for a letterpress perfecting rotary printingpress cannot, however, conveniently be arranged so that the webs bothrun in the `same direction because Ithe web then winds itself up andcannot be drawn out simply to the folder and delivery, except sidewaysby means of a turner bar, unless the delivery or reel stand is envelopedby the web run. This is undesirable as the web run is then wastefullyextended. Fortunately, in connection with such a machine the heatrequired to dry the -second printing can be appreciably less than thatrequired for the first printing and, this being so it is considered thatthe second printing run can tbe made .the lower web through the drier,and travel the opposite way to the rst run, .e. towards the burners.This system does not result in as high Van etliciency as when both webstravel in the same direction but is nevertheless thought to be practicalwhen circumstances dictate its desirability.

I claim:

1. Apparatus for drying two substantially parallel webs of paper-likematerial comprising la drying chamber having opposed entrance and exitapertures, web vfeeding means and heat generating means, said webfeeding means comprising two spaced apart rollers adjacent to andexterior of said drying chamber at said entrance aperture and 4twospaced 'apart rollers adjacent to and exterior of said drying chamber atsaid exit aperture, and said heat generating means comprising at leastone gas burner having an -axial outlet and adapted to generate a lazyflame, said burner being exterior of said drying chamber Iand positionedbetween said spaced apart rollers adjacent to said entrance aperturewith said burner axis outlet in alignment with both of said apertures.

2. Apparatus as set forth in claim l in which said spaced apart rollersadjacent said exit aperture `are closer together than said spaced apartrollers adjacent said entrance aperture.

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